This invention pertains generally to electrical measuring apparatus and more particularly to a transmitter for conveying information from a rotating member to a stationary monitor.
Heretofore, there have been some attempts to monitor conditions and make measurements on rotating members by means of sensing elements and transmitters mounted on the members for conveying information to suitable monitoring and processing equipment located remotely of the members. Examples of such measurements include temperature and stress measurements in jet engines and other turbines, stress measurements in gears, and voltage and current measurements in generators and other rotating electrical machines.
In many such measurements, the transmitters are subjected to severe environments. For example, when mounted on the rotor of a jet engine, a transmitter is typically exposed to a centrifugal force on the order of 30,000 G's. In order to withstand such forces, a transmitter must be very strong mechanically, and at the same time it must be small enough to avoid interfering with the normal operation of the machine in which it is installed.
Transmitters heretofore provided for use in such measurements have utilized a combination of hybrid circuits and discrete components encased in a body of potting material with pins for connection to external components such as sensing elements and a power supply. The hybrid circuits comprise a ceramic substrate on which circuit components are mounted in integrated form, and the hybrid circuit is generally mounted in a package having leads connected to the components on the substrate. In prior art transmitters, the leads are utilized in making connections between the hybrid circuits and the discrete components and connecting pins. Although suitable for some applications, transmitters constructed in this manner are too large for other applications and not strong enough for severe environments such as jet engines.